Ceramic and metallic components each have characteristics that are beneficial in some aerospace applications and detrimental in others. For example, ceramic components tend to exhibit sensitivity to localized contact stress, have low tolerance for strain or tension, and exhibit brittle behavior. However, ceramics have good compression properties and good tolerance to high temperatures. Metallic components typically have higher tolerance for local contact stress, handle elastic and plastic strain well, and better tension properties compared to ceramics, but have lower tolerance for high temperatures as compared to ceramics. Ceramics generally have lower coefficients of thermal expansion than metals.
It is often beneficial to utilize ceramic components in some areas of the engine while using metallic components in other areas. The metallic and ceramic components must be mechanically coupled to one another in many cases. Due to the differences in the coefficients of thermal expansion, ceramic and metallic components that experience large temperature ranges in operation cannot be directly connected.